Vitamins are required in trace amounts in the diet for health, growth and reproduction.
As the chemical structure of the vitamin became known through its isolation and synthesis; it was given a chemical name. When the chemical name was assigned, it was assumed that the name applied to one substance with one specific activity.
Some of the vitamins occur in foods in a form known as precursors or provitamin. Once inside the body, these are transformed chemically to one or more active vitamin forms.
Now it is evident that a vitamin may have a variety of functions and that vitamin activity may be found in several closely related compounds known as vitamers. An excellent example of this is vitamin A, which has several seemly unrelated functions and encompasses not only retinol but also retinal and retinoic acid.
The vitamins can further classified into two classes: fat soluble and water soluble. Soluble confers vitamin many of their characteristics. It determines how they are absorbed into and transported by the bloodstream.
The fat soluble vitamins are represented by vitamins A, D, E, and K absorbed and transported by conventional lipid transport.
For water-soluble vitamins, respective solubility coefficients are major factors that dictate the availability and ease of absorption.
What are vitamins?
